JCMT finds hints of Life on Venus

Credit: ALMA (ESO/NAOJ/NRAO), Greaves et al. & JCMT (East Asian Observatory)

Released: 14 September, 2020, Academia Sinica, Institute of Astronomy & Astrophysics, Taiwan

MAUNAKEA HAWAI`I - An international team of astronomers, led by Professor Jane Greaves of Cardiff University, UK, today announced the discovery of a rare molecule – phosphine – in the clouds of Venus. On Earth, this gas is only made industrially, or by microbes that thrive in oxygen-free environments. The detection of phosphine could point to such extra-terrestrial “aerial” life. “When we got the first hints of phosphine in Venus’s spectrum, it was a shock!”, said Jane, who first spotted signs of phosphine in observations from the James Clerk Maxwell Telescope (JCMT) in Hawai`i.

Paul Ho, Academician of Academia Sinica, the Director General of the EAO comments: "The EAO/JCMT has been producing very exciting results for the past few years. The M87 black hole shadow results and the Venus phosphine detection continue to exploit the great potentials for mm/submm window, especially when working in concert with other telescopes like ALMA and EHT."

Venus the phosphine molecule and the phosphine detection by JCMT (white) and ALMA (orange). Image credit: Joanna Pętkowska, PhD.

Astronomers have speculated for decades that high clouds on Venus could offer a home for microbes – floating free of the scorching surface, with access to water and sunlight, but needing to tolerate very high acidity. The detection of phosphine, which consists of hydrogen and phosphorus, could point to this extra-terrestrial ‘aerial’ life. The new discovery is described in a paper published today in Nature Astronomy.

Artistic impression of Venus depicting a representation of phosphine molecule shown in the inset. The molecules were detected in the Venusian high clouds in data from the James Clerk Maxwell Telescope and the Atacama Large Millimeter/submillimeter Array. Astronomers have speculated for decades that life could exist in Venus’s high clouds. The detection of phosphine could point to such extra-terrestrial “aerial” life. Image credit: ESO/M. Kornmesser/L. Calçada & NASA/JPL/Caltech

The first detection of phosphine in the clouds of Venus was made using the JCMT in Hawai`i, which is operated by the East Asian Observatory (EAO). The team were subsequently awarded time to follow up their discovery with 45 telescopes of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. Both facilities observed Venus at a wavelength of about 1 millimeter, much longer than the human eye can see – only telescopes at high altitude can detect it effectively. “In the end, we found that both observatories had seen the same thing — faint absorption at the right wavelength to be phosphine gas, where the molecules are backlit by the warmer clouds below” said Jane.

The astronomers then ran calculations to see if the phosphine could come from natural processes on Venus. Massachusetts Institute of Technology scientist Dr William Bains led the work on assessing natural ways to make phosphine. Some ideas included sunlight, minerals blown upwards from the surface, volcanoes, or lightning, but none of these could make anywhere near enough of it. Natural sources were found to make at most one ten thousandth of the amount of phosphine that the telescopes saw. In contrast the team found that in order to create the observed quantity of phosphine on Venus, terrestrial organisms would only need to work at about 10% of their maximum productivity. Any microbes on Venus will though likely be very different to their Earth cousins. Earth bacteria can absorb phosphate minerals, add hydrogen, and ultimately expel phosphine gas.

Team member and MIT researcher, Dr Clara Sousa Silva, had thought about searching for phosphine as a ‘biosignature’ gas of non-oxygen-using life on planets around other stars, because normal chemistry makes so little of it. She comments “Finding phosphine on Venus was an unexpected bonus! The discovery raises many questions, such as how any organisms could survive. On Earth, some microbes can cope with up to about 5% of acid in their environment – but the clouds of Venus are almost entirely made of acid.”

The team believes this discovery is significant because they can rule out many alternative ways to make phosphine, but they acknowledge that confirming the presence of “life” needs a lot more work. Although the high clouds of Venus have temperatures up to a pleasant 30 degrees centigrade, they are incredibly acidic – around 90% sulphuric acid – posing major issues for microbes to survive there. Prof Sara Seager and Dr Janusz Petkowski, both at MIT, are investigating how microbes could shield themselves inside scarce water droplets.

The team are now eagerly awaiting more telescope time to establish whether the phosphine is in a relatively temperate part of the clouds, and to look for other gases associated with life. This result also has implications in the search for life outside our Solar system.

The 19 authors who contributed to the first detection of phosphine on Venus.

From Top row: Jane Greaves, Helen Fraser, Annabel Cartwright, alma e Sousa-Silva, Sara Seager,

Middle top row: Hideo Segawa, Emily Drabek-Maunder, Janusz Petkowski, Paul Rimmer.

Middle bottom row: Zhuchang Zhan, William Bains, Ingo Mueller Wodarg, Sukrit Ranjan.

Bottom row: Per Friberg, Anita Richards, Jim Hoge, E’Lisa Lee, Iain Coulson, David Clements.

On hearing the results of the JCMT study, the JCMT’s Deputy Director Dr Jessica Dempsey said “These results are incredible” and went on to say “this discovery made in Hawai`i, by the JCMT, was made with a single pixel instrument. This is the very same instrument that also took part in capturing the first image of a Black Hole, Pōwehi. The discovery of phosphine in the atmosphere of Venus really showcases the breadth of cutting-edge research undertaken by astronomers using the JCMT. I am so pleased of the efforts from all our staff here in Hawai`i”

The JCMT instrument that captured this phosphine discovery has since retired and been replaced by a new and more sensitive instrument known as Nāmakanui. On the potential of this new instrument, Jessica commented “Like it’s namesake, the big-eyed fish hunting food in the dark waters, we will turn the far more sensitive Nāmakanui back to Venus in this hunt for life in our universe. This is just the beginning, and I’ve never been more excited to be a part of our boundary-pushing JCMT team.”

JCMT open for morning observing with the shadow of Maunakea evident behind as it rises over Hualālai. JCMT is able to observe during the daytime as it operates at sub-millimeter wavelengths. Image credit: Tom Kerr, UKIRT.

JCMT Deputy Director, Jessica Dempsey stands beside the now retired instrument, RxA3m, that made this first detection of phosphine on Venus. The instrument has since been replaced by a more powerful instrument called Nāmakanui, that is available to all EAO astronomers. Image Credit: Harriet Parsons

More Information:

This research was presented in the paper “Phosphine Gas in the Cloud Decks of Venus” appears in Nature Astronomy.

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Original source: JCMT Press Release

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